Vortex generators are flow control devices that may improve the performance of a vehicle by generating vortices that passively energize low-energy areas of a fluid medium flowing over the vehicle. For example, vortex generators may be mounted on an aircraft to energize the boundary layer of local airflow over an aerodynamic surface and thereby reduce or eliminate the tendency of the downstream airflow to separate from the aerodynamic surface. By reducing or eliminating flow separation, vortex generators may improve the performance of an aircraft such as by reducing aerodynamic drag, increasing the aerodynamic buffet margin, and improving the handling qualities of the aircraft at high angles of attack. A reduction in aerodynamic drag may result in an improvement in the range, fuel efficiency, maximum speed, and high-lift (e.g., low speed) characteristics of the aircraft. Vortex generators may also improve performance by increasing aerodynamic lift at a given angle-of-attack or by maintaining lift with increasing angle-of-attack (i.e., delaying stall).
Unfortunately, existing designs for passive vortex generators may protrude above the outer mold line of an aircraft and therefore do not meet aircraft survivability constraints such as line-of-sight requirements. Line-of-sight requirements may necessitate that certain objects on an aircraft are hidden from view when the aircraft is observed from certain directions. Non-passive flow control devices such as active flow control systems may improve aerodynamic performance by suctioning a portion of the boundary layer through small perforations in an aerodynamic surface. Such active flow control systems may be integrated into the outer mold line of an aircraft and may therefore meet line-of-sight requirements. However, active flow control systems may add significant complexity and weight to an aircraft and may require continuous power to operate.
As can be seen, there exists a need in the art for a passive vortex generator that may improve vehicle performance while meeting line-of-sight requirements.